The present invention relates to a device and a method for regulating the energy supply for ignition in an internal combustion engine.
A device and a method for regulating the energy supply for ignition in an internal combustion engine is described in xe2x80x9cTechnische Unterrichtung, Kombiniertes Zxc3xcnd- und Benzineinspritzsystem mit Lambda-Regelung-Motronik Technical Information, Combined Ignition and Gasoline Injection System With Lambda Regulation Engine Management Systemxe2x80x9d, Robert Bosch GmbH, 1983. In that document, on page 11, a dwell angle control is described, the energy, continuously increased over the dwell time and reached at the point of ignition, stored in the magnetic field of the ignition coil, which, as a first approximation is proportional to the square of the attained primary current value, is changed as a function of a characteristics map. In this context, the characteristics map is a function of the battery voltage and the engine speed.
Furthermore, in German Patent Application No. 199 563 81.0 a device and a method for ignition of an internal combustion engine is described in which the turn-on time, i.e., the time difference between the energizing edge in the signal line, which corresponds to the beginning of current flow through the primary winding, and the point in time at which the primary current reaches a first threshold value, is ascertained. The turn-on time is determined in the light of the signals in the signal line and signals in one or more diagnostic lines, which connect a central control unit to the ignition power module.
The device and method, respectively, according to the present invention may provide the advantage that it is ensured that there will be no overheating of the ignition power module, i.e., that a maximum allowable power loss, which drops in ignition power module 13, is not exceeded, and, on the other hand, a sufficient energy supply is present for the ignition. In this connection, the non-exceeding of the maximum power loss has priority. Thus, direct reactions may be formed to changes in the primary winding coming about during the running time of the engine, such as newly occurring short circuits, i.e., coil and wiring harness defects. In this context, the regulation may occur in both directions, that is, in the direction of an increase or a decrease in the energy supply.
It may be advantageous that the ignition power module temperature may be ascertained, in the light of the power loss dropping off in the ignition power module, with the aid of the temperature of the surroundings of the ignition power module, in order to avoid damage, the ignition power module having to be switched off when the temperature of the ignition power module is too high. Here, it may be advantageous to ascertain the temperature of the surroundings of the ignition power module using a temperature sensor, since in that manner a very accurate reading of the surrounding temperature is possible. It may also be advantageous to read out the surrounding temperature of the ignition power module, with the aid of a predefined value or as a function of certain operating states, from a characteristics map from a memory unit of the central control unit, since then no temperature sensor will be needed. Furthermore, if a temperature sensor is present, it may be advantageous to use the characteristics map""s functional dependency of the surrounding temperature of the ignition power module to check the functional capability of the temperature sensor, and, in the failure case, to replace the surrounding temperature ascertainment, using the sensor, by the characteristics map. It may also be advantageous to calculate the used power loss due to line resistances and winding resistances which are temperature-dependent, in the light of the ascertained temperature of the primary winding, and to give consideration to this in making available the energy supply.
Example embodiments of the present invention are illustrated in the drawings and are explained in greater detail in the following description.